- Having a sponge or towel left in after surgery? (40 patients per week)
- Having a surgery performed on the wrong side of the body? (20 patients per week)
- Having the wrong operation altogether? (20 patients per week)

"The public scratches their head and say, come on, you've got to be kidding me about this," says Dr. Peter Pronovost, V.P. of Patient Safety at Johns Hopkins Medicine and co-author of the study. Even so, those numbers may underreport the risk of these "never events." The study used data from malpractice claims, but many instances of surgical error never get that far.

Patient safety advocates like Pronovost worry that there aren't adequate systems to watch for these kinds of errors. In the case of sponges, many operations require a great number of surgical instruments, increasing the risk that one may stay in the body.

"The way we keep track of whether we left [a sponge] in you, is simply counting what went in, and counting when they came out."

Pronovost says errors like these have always been a problem, and hospitals are working hard to fix them. He's concerned that cuts in payments to hospitals in the Affordable Care Act will put even more stress on medical professionals already working long hours.

"What health care hasn't done is use technology to improve productivity. It's largely relied on the heroism of doctors and nurses to keep safe, and now we're asking for even greater heroism," Pronovost says. "We really have to start saying, it's time for technology to start leading the way."

Dr. Pronovost offers a number of practical tips for patients:

-Be an active participant in your care. Those who learn a lot about their course of treatment tend to have better outcomes.
-Have an advocate like a family member with you in the hospital.

When you arrive for surgery:

- Talk to the surgeon while you and your family are in the waiting area.
- Identify yourself.
- Tell the doctor what operation you plan to have, and on which side of your body.
- Make sure you or a medical attendant marks the area to be operated.
- Ensure that's the operation the surgeon plans to perform.
- Your doctor should make sure all the paperwork, like consent forms and medical records, matches, listing your name and your date of birth.

Sarah Gardner is a reporter with Marketplace's Sustainability Desk. Her past projects include “We Used To Be China,” “Coal Play,” “Consumed,” “The Next American Dream,” “Jobs of the Future,” and “Climate Race,” among others. Sarah began her career at Marketplace as a...